Protective material ring

ABSTRACT

Provided is a protective material ring in which a plurality of silicon members are joined. A protective material ring is to be installed in a treatment chamber of a substrate treatment apparatus performing plasma treatment on a substrate, and the substrate is accommodated in the treatment chamber. The protective material ring includes: three or more silicon members; and a joining part joining the silicon members. The joining part contains boron oxide.

TECHNICAL FIELD

The present invention relates to a protective material ring.

BACKGROUND ART

A dry etching apparatus using plasma is used as a substrate treatmentapparatus in manufacture of a semiconductor integrated device such as anLSI. The dry etching apparatus includes a cylindrical vacuum chamber.While a wafer to be etched is placed on a cathode of a planar electrodeand etching gas is introduced into the vacuum chamber, a high-frequencyvoltage is applied between the cathode and a counter electrode (anode)by a high-frequency oscillator to generate plasma of the etching gasbetween the electrodes. Positive ions as activated gas in the plasmaenter a surface of the wafer to etch the wafer.

Various ring-shaped members are used in the vacuum chamber of the dryetching apparatus. Representative examples of the ring-shaped memberinclude a focus ring that has a doughnut shape surrounding the wafer tobe etched and an annular ground ring placed so as to cover a sidesurface of a columnar susceptor base portion on which the wafer ismounted. Examples further include protective materials such as anannular shielding ring provided on a peripheral portion of the counterelectrode and a side-wall member that covers an inner-wall side surfaceof the vacuum chamber (Patent Literature 1).

A silicon component is desired to be used in the vacuum chamber of thedry etching apparatus because a metal component causes metalcontamination when the metal component is used. It is necessary for thefocus ring, the ground ring, and the ring-shaped protective materials toeach have a diameter larger than that of the wafer to be etched. Asilicon component for 300 mm wafer, which is mainly in current use, isexpensive because the silicon component is fabricated from a siliconcrystal ingot having a diameter of 320 mm or more. In particular, thediameter of some ring-shaped side-wall members reaches 700 mm or more,and it may be virtually impossible to fabricate the ring-shapedside-wall members from silicon crystal ingots.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Patent Laid-Open No. 2008-251744

SUMMARY OF INVENTION Technical Problem

If the silicon component can be manufactured by joining a plurality ofsilicon members, not from a one-piece component, silicon crystal ingotsthat have a smaller diameter can be used for fabrication of the siliconcomponent. Therefore, various advantages such as manufacturing costreduction are expected.

An object of the present invention is to provide a protective materialring in which a plurality of silicon members are joined together.

Solution to Problem

A protective material ring according to the present invention is aprotective material ring to be installed in a treatment chamber of asubstrate treatment apparatus performing plasma treatment on asubstrate, and the substrate is accommodated in the treatment chamber.The protective material ring includes: three or more silicon members;and a joining part joining the three or more silicon members. Thejoining part contains boron oxide.

A protective material ring according to the present invention is aprotective material ring to be installed in a treatment chamber of asubstrate treatment apparatus performing plasma treatment on asubstrate, and the substrate is accommodated in the treatment chamber.The protective material ring includes: three or more silicon members;and a joining part joining the three or more silicon members. Thejoining part contains any one of Al, Ga, Ge, and Sn, and is a eutecticalloy with silicon, the silicon members include two or more arc-shapedsilicon members and an embedded silicon member that is embedded at aposition across the arc-shaped silicon members, and the joining partjoining the arc-shaped silicon members and the embedded silicon memberis provided between the arc-shaped silicon members and the embeddedsilicon member.

Advantageous Effects of Invention

According to the present invention, it is possible to manufacture theprotective material ring by combining a plurality of silicon memberseach cut out from a silicon crystal ingot that has a size smaller thanan outer diameter of the protective material ring. Therefore, a siliconcrystal ingot that has a size larger than the outer diameter of theprotective material ring does not necessarily need to be used for theprotective material ring, and hence the cost can be accordingly reduced.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view schematically illustrating aconfiguration of a dry etching apparatus that includes the siliconcomponent fabricated from a protective material ring according to afirst embodiment.

FIG. 2 is a perspective view illustrating the protective material ringaccording to a first embodiment.

FIG. 3 is a cross-sectional view illustrating an abutting surfaceaccording to a first embodiment.

FIG. 4 is a cross-sectional view schematically illustrating an apparatusmanufacturing the protective material ring.

FIG. 5 is a cross-sectional view illustrating a modification of thefirst embodiment.

FIG. 6 is a perspective view illustrating a protective material ringaccording to a second embodiment.

FIG. 7A is a cross-sectional view illustrating an abutting surfaceaccording to a second embodiment, where FIG. 7A illustrates an abuttingsurface of a first ring body.

FIG. 7B is a cross-sectional view illustrating an abutting surfaceaccording to a second embodiment, where FIG. 7B illustrates an abuttingsurface of a second ring body.

FIG. 8A is a cross-sectional view illustrating modifications of thesecond embodiment, where FIG. 8A is a modification (1).

FIG. 8B is a cross-sectional view illustrating modifications of thesecond embodiment, where FIG. 8B is a modification (2).

FIG. 9A is a perspective view illustrating a protective material ringaccording to a third embodiment, where FIG. 9A illustrates top surfaceside.

FIG. 9B is a perspective view illustrating a protective material ringaccording to a third embodiment, where FIG. 9B illustrates bottomsurface side.

FIG. 10 is a cross-sectional view illustrating an abutting surfaceaccording to the third embodiment.

FIG. 11A is a plan view illustrating an embedded silicon member, whereFIG. 11A illustrates a modification (1).

FIG. 11B is a plan view illustrating an embedded silicon member, whereFIG. 11B illustrates a modification (2).

FIG. 12A is a cross-sectional view illustrating modifications of theabutting surface according to the third embodiment, where FIG. 12Aillustrates a modification (1).

FIG. 12B is a cross-sectional view illustrating modifications of theabutting surface according to the third embodiment, where FIG. 12Billustrates a modification (2).

DESCRIPTION OF EMBODIMENT

Some embodiments of the present invention are described in detail belowwith reference to drawings.

1. First Embodiment

(1) Overall Configuration

A dry etching apparatus 10 illustrated in FIG. 1 includes a vacuumchamber 12 as a treatment chamber, an upper electrode plate 14, and abase 16. The vacuum chamber 12 is substantially cylindrical and has atreatment space 31 surrounded by a cylindrical side wall on the innerportion thereof. The inner surface of the side wall of the vacuumchamber 12 is covered with a side-wall member 13. The inner surface onthe periphery of the upper electrode plate 14 on the upper wall of thevacuum chamber 12 is covered with an upper-wall member 17. The side-wallmember 13 and the upper-wall member 17 are annular members forprotecting the inner wall of the vacuum chamber 12 that is exposed toplasma, and are made of silicon.

A baffle plate 25 that partitions the inside of the vacuum chamber 12 inthe height direction is provided in the vacuum chamber 12. The inside ofthe vacuum chamber 12 partitioned by the baffle plate 25 has a lowerside on which an exhaust space 26 is formed and an upper side on whichthe treatment space 31 is formed. The baffle plate 25 is a protectivemember for preventing the backflow of etching gas, and is made ofsilicon. The baffle plate 25 has an annular main body, and includes aflow passage 27 that passes through the main body in the thicknessdirection. As illustrated in this figure, the baffle plate 25 isprovided substantially in the center of the inside of the vacuum chamber12 in the height direction.

The upper electrode plate 14 is a disc-like member, and is fixed to anupper portion in the vacuum chamber 12. The peripheral edge portion ofthe upper electrode plate 14 is covered with a protective ring 20. Ashielding ring 21 made of quartz is provided between the upper electrodeplate 14 and the protective ring 20. The protective ring 20 is a memberfor protecting the inner wall of the vacuum chamber 12 from plasmagenerated near the upper electrode plate 14, and is made of silicon. Theprotective ring 20 may be grounded. In this figure, the surface of theprotective ring 20 on the inner side of the vacuum chamber 12 protrudesmore than the shielding ring 21 and is flush with the upper-wall member17. The upper electrode plate 14 includes a plurality of through holes15 each penetrating through the upper electrode plate 14 in a thicknessdirection. The upper electrode plate 14 is electrically connected with ahigh-frequency power supply that is not illustrated in the figure. Theupper electrode plate 14 is connected with a gas supply pipe 24.

Etching gas supplied through the gas supply pipe 24 flows into thevacuum chamber 12 from the through holes 15 of the upper electrode plate14. The etching gas flowing into the vacuum chamber 12 flows into theexhaust space 26 through the flow passage 27, and is exhausted to theoutside from an exhaust port 28.

The base 16 is disposed in the treatment space 31 on the upper side ofthe baffle plate 25 in the vacuum chamber 12, and the periphery thereofis surrounded by a ground ring 30. The ground ring 30 is made ofsilicon, and is grounded. The focus ring 18 is provided on the base 16.The focus ring 18 is made of silicon, and a concave part 19 supporting aperipheral edge of a wafer 22 is provided over an entire innercircumference. The focus ring is electrically connected with a powersupply that applies voltage for stabilizing the plasma during etchingtreatment. A cover ring 23 that protects the side surface of the focusring 18 may be provided on the periphery of the focus ring 18. The coverring 23 is made of quartz, and has a concave part 33 supporting aperipheral edge of the focus ring 18 formed over an entire innercircumference thereof.

The dry etching apparatus 10 is supplied with the etching gas throughthe upper electrode plate 14. When the high-frequency voltage is appliedfrom the high-frequency power supply, plasma is generated between theupper electrode plate 14 and the wafer 22. The surface of the wafer 22is etched by this plasma.

The protective material ring according to the present embodiment isapplicable to the side-wall member 13, the upper-wall member 17, theprotective ring 20, and the baffle plate 25 serving as siliconcomponents. The protective material ring is not limited to the siliconcomponents described above. The protective material ring can be appliedto silicon components disposed in the vacuum chamber 12 of the dryetching apparatus 10 other than the focus ring 18 that is a ring for anelectrode and the ground ring 30 that is a ring for an electrode. Theprotective material ring can have an inner diameter of about 320 mm ormore and an outer diameter of about 800 mm or less.

As an example the protective material ring according to the presentembodiment that serves as the member of the protective ring 20 isdescribed below. As illustrated in FIG. 2 , a protective material ring32 includes a plurality of (three in this figure) first silicon members34, 36, and 38. Note that, in the following description, in a case wherethe plurality of first silicon members 34, 36, and 38 is notparticularly distinguished from one another, these are collectivelyreferred to as silicon members. The silicon members each have an arcshape, and are integrated in a ring shape by joining abutting surfaces37A that are end faces of the silicon members in a longitudinaldirection, in one direction through joining parts (not illustrated inthe figure). The silicon members each may contain monocrystallinesilicon or polycrystalline silicon, and a manufacturing method, purity,crystal orientation, etc. thereof are not limited. Although a size ofeach of the silicon members is not particularly limited, each of thesilicon members has, for example, a thickness of about 1 mm or more andabout 100 mm or less, and a width of about 10 mm or more and about 100mm or less.

As illustrated in FIG. 3 , a joining part 39 and a silicon adhesion part40 are provided between the abutting surfaces 37A of the siliconmembers. FIG. 3 illustrates the abutting surface 37A of the firstsilicon member between the first silicon members 34 and 36. A directionof an arrow in the figure indicates an outside direction in a radialdirection of the protective material ring 32.

Each of the joining parts 39 is provided at a center part except for arange of several mm from outer edges of the abutting surfaces 37A, andis preferably provided at the center part except for a range of 1 mm ormore. The joining part 39 is made of a eutectic alloy of silicon andsilicon containing a metal forming a eutectic alloy with silicon. Themetal forming a eutectic alloy with silicon is any one of Al, Ga, Ge,and Sn (hereinafter, also referred to as “alloying metal”). The metalsAl, Ga, Ge, and Sn are preferable because each of the metals has a lowdiffusion coefficient in silicon crystal and is little diffused in asilicon member, hardly forms a deep level that becomes an electricproblem, and has no influence on environment. The most preferable metalis Al because of low price. The purity of the alloying metal is notparticularly limited as long as the alloying metal can form a eutecticwith silicon, and the purity of the alloying metal is preferably 98% ormore.

Each of the silicon adhesion parts 40 is provided on the outer edges ofthe abutting surfaces 37A, and plugs the gap between the abuttingsurfaces 37A. The silicon adhesion parts 40 are preferably provided atparts that are not in contact with the vacuum chamber 12, the upper-wallmember 17 and the shielding ring 21, are exposed inside the vacuumchamber 12, and are to be exposed to plasma in dry etching, namely, onthe top surface side of the protective material ring 32 out of the outeredges of the abutting surfaces 37A. Further, the silicon adhesion parts40 are more preferably provided also on inner peripheral surface sideout of the outer edges of the abutting surfaces 37A, in addition to thetop surface side. Each of the silicon adhesion parts 40 plugs the gapbetween the abutting surfaces 37A to be irradiated with plasma, therebypreventing the eutectic alloy at the joining part 39 from being exposed.

(2) Manufacturing Method

Next, a method of manufacturing the protective material ring 32 isdescribed. First, surface treatment is performed on the silicon members.More specifically, surfaces of the respective silicon members aretreated by grinding, polishing, or the like, to preferably form mirrorsurfaces. The surfaces of the respective silicon members may be etchedby mixed solution of hydrofluoric acid and nitric acid. As the mixedsolution, chemical polishing solution (hydrofluoric acid (49%):nitricacid (70%):acetic acid (100%)=3:5:3) standardized as JIS H 0609 may beused.

Subsequently, the three first silicon members 34, 36 and 38 are arrangedin the ring shape. An alloying metal foil is disposed between theabutting surfaces 37A of the first silicon members 34, 36 and 38. Athickness of the alloying metal foil is preferably small in terms ofreduction in energy for melting. The thickness of the alloying metalfoil is preferably 0.1 μm to 100 μm, and more preferably 0.5 μm to 20 μmto exert joining strength. If the thickness of the alloying metal foilis lower than the above-described lower limit value, the alloying metalfoil is easily damaged when disposed on the joining surface. If thethickness of the alloying metal foil is larger than the above-describedupper limit value, a part where joining with silicon is insufficient iseasily generated.

Next, heating is performed from the outer side of the silicon members,to generate a melt containing silicon and the alloying metal. Theheating method is not particularly limited, and the heating can beperformed through resistance heating, optical heating, etc. The opticalheating is preferable because positions to be heated can be easilyshifted, and a heating amount can be easily changed based on thesupplied power. For example, various kinds of lamps and lasers are used.

In the present embodiment, an apparatus illustrated in FIG. 4 can beused. The apparatus illustrated in the figure includes at least one lamp42 and at least one elliptical mirror 44 as a light condensing portionthat condenses light emitted from the lamp 42. As the lamp 42, a xenonlamp or a halogen lamp that is commonly used in an infrared crystalgrowth apparatus is usable. An output of the lamp is preferably about 1kW to about 30 kW.

The heating may be performed from an oblique direction without beinglimited to a direction perpendicular to the silicon members as long asthe heating is performed from the outer side of the abutting surfaces37A. The alloying metal foil is first melted by the heating and a metalmelt is generated. Next, the abutting surfaces 37A of the siliconmembers in contact with the metal melt are attacked by the metal melt,and a melt containing silicon is generated. It is considered that whenthe heating is stopped and temperature is lowered, the melt issolidified while forming an alloy phase containing a eutectic, andjoining is completed. For example, in a case where an Al foil as thealloying metal foil is used, the silicon members can be sufficientlyjoined by heating up to about 800° C.

A light focused region normally has a diameter of about 10 mm to about30 mm. The diameter of the light focused region is increased to about 30mm to about 100 mm when a light emission position of the lamp 42 is outof position from a focal point of an elliptical mirror 44. The lightfocused region thus expanded makes it possible to expand a heated range.The light focused region is preferably moved to scan the entire topsurface of the protective material ring 32 at the abutting surfaces 37A,to effect heating.

Next, the melt containing silicon and the alloying metal is cooled andsolidified to generate the joining part 39 containing a eutectic alloy.When the alloying metal is Al and is cooled up to about 577° C., thejoining part 39 containing Al-silicon eutectic (12.2 atomic % Al) isgenerated. A cooling speed depends on the alloying metal to be used. Inthe case where Al as the alloying metal is used, the cooling speed ispreferably controlled to 10 to 100° C./min. If the cooling speed islower than the above-described lower limit value, a cooling time islengthened and efficiency is low. If the cooling speed is higher thanthe above-described upper limit value, distortion tends to remain in thejoining part 39. The cooling speed can be controlled by graduallyreducing the output of heating means after melting of the alloying metalfoil is completed, and stopping the heating when the temperature of thejoining part 39 is estimated to be lower than melting temperature of theeutectic. Such control of the heating temperature can be performed basedon a result of a measurement of relationship between power of theheating means and the temperature. The measurement is previouslyperformed, for example, while a thermocouple having a shape similar tothe silicon members to be actually pasted together is disposed betweenthe silicon members.

Generation of the melt by the heating and generation of the joining part39 containing the eutectic alloy by the cooling described above arepreferably performed inside a chamber of argon atmosphere of 10 torr to200 torr (about 1333 Pa to about 26664 Pa) in order to prevent oxidationof the alloying metal and silicon. It is also possible to preventoxidation by decompression without using argon gas; however, this is notpreferable because decompression causes evaporation of silicon and theinside of the chamber may be contaminated. Further, oxidation can beprevented by nitrogen gas; however, this is not preferable becausesilicon is nitrided at temperature of 1200° C. or more.

Next, the silicon adhesion parts 40 are described. One silicon adhesionpart 40 between the abutting surfaces 37A of each two of the firstsilicon members 34, 36, and 38 is formed by heating and melting siliconnear the abutting surfaces 37A. First, expansion of the ellipticalmirror 44 at the irradiation position is set to about 3 mm by adjustinga position of the lamp such that a focal position of an ellipticalmirror 44 and a position of a light emitting unit of the lamp 42 arecoincident with each other, and adjusting a height of the top surface ofthe silicon members so as to be coincident with another focal point ofthe elliptical mirror 44. In this state, the position of the ellipticalmirror 44 is adjusted to the positions of the abutting surfaces 37A, andpower of the lamp 42 is increased. When heating is started, the topsurface side of the abutting surfaces 37A is melted to generate siliconmelt. More specifically, the surface starts to melt at 60% of rated lamppower (estimated surface temperature is 1420° C.), and the silicon meltflows into the gap between the abutting surfaces 37A to plug a part ofthe gap between the abutting surfaces 37A at 90% of the rated lamppower. In this state, the elliptical mirror 44 is moved for scanningalong the abutting surfaces 37A at a constant speed, for example, at aspeed of 5 mm/min, which makes it possible to plug the gap between theabutting surfaces 37A with the silicon melt. The elliptical mirror 44 ispreferably moved to scan the top surface side and the inner peripheralsurface side of the protective material ring 32 out of the outer edgesof the abutting surfaces 37A, to effect heating.

Next, the top surfaces of the melted abutting surfaces 37A are cooled tocrystallize the silicon melt based on crystal of the silicon members.More specifically, the power of the lamp 42 is reduced, in two minutes,to 55% of the rated lamp power at which the silicon melt starts to besolidified, and the state is maintained for five minutes.

The joining parts 39 and the silicon adhesion parts 40 are similarlyformed at all of the abutting surfaces 37A through the above-describedprocedure, which makes it possible to join the first silicon members 34,36, and 38 to form the protective material ring 32.

The protective material ring 32 obtained in the above-described mannerserves as the protective ring 20. The protective ring 20 is mounted on aperipheral edge part of the upper electrode plate 14 so that the topsurface at which the silicon adhesion parts 40 are provided on theabutting surfaces 37A faces downward and the bottom surface is incontact with the upper wall of the vacuum chamber 12.

The protective material ring 32 is manufacturable by combining three ormore silicon members that are each cut out from a silicon crystal ingotfor wafer having a size smaller than the outer diameter of the side-wallmember 13, the upper-wall member 17, the protective ring 20, and thebaffle plate 25. Accordingly, it is unnecessary for the protectivematerial ring 32 to use the silicon crystal ingot for wafer that has asize larger than the outer diameter of the side-wall member 13, theupper-wall member 17, the protective ring 20, and the baffle plate 25,which allows for reduction of the cost.

Since the protective material ring 32 according to the presentembodiment includes the silicon adhesion parts 40 at the abuttingsurfaces 37A, it is possible to prevent the eutectic alloy at thejoining parts 39 from being exposed. Accordingly, even when theprotective material ring 32 is to be irradiated with plasma inside thevacuum chamber 12, it is possible to prevent the inside of the vacuumchamber 12 from being contaminated by the eutectic alloy.

The case where the silicon adhesion part 40 is provided on the topsurface side and the inner peripheral surface side of the protectivematerial ring 32 out of the outer edges of the abutting surfaces 37A hasbeen described in the present embodiment; however, the present inventionis not limited thereto. The silicon adhesion part 40 may be provided onthe top surface side and the outer peripheral surface side out of theouter edges of the abutting surfaces 37A, or may be provided on entirecircumferences of the outer edges of the abutting surfaces 37A.

The case where the silicon adhesion parts 40 are provided between theabutting surfaces 37A of the first silicon members 34, 36, and 38 hasbeen described in the present embodiment; however, the present inventionis not limited thereto. As illustrated in FIG. 5 , the silicon adhesionparts do not necessarily need to be provided between the abuttingsurfaces 37B.

2. Second Embodiment

Next, a protective material ring according to a second embodiment isdescribed. Note that components similar to the components according tothe above-described first embodiment are denoted by like referencenumerals, and description thereof is omitted. A protective material ring46 illustrated in FIG. 6 includes the first ring body 32 and a secondring body 47. The first ring body 32 is the same as the protectivematerial ring according to the above-described first embodiment. Thesecond ring body 47 includes a plurality of (three in the figure) secondsilicon members 48, 50, and 52. Although the reference numerals aredifferent for convenience of description, the second silicon members 48,50, and 52 are the same as the first silicon members 34, 36, and 38. Thefirst ring body 32 and the second ring body 47 are coaxially superposedthrough joining surfaces 54A while abutting surfaces 37A of the siliconmembers of the first ring body 32 are out of position in acircumferential direction from abutting surfaces 37A of the siliconmembers of the second ring body 47.

As illustrated in FIGS. 7A and 7B, the joining part 39 and the siliconadhesion part 40 are provided between the abutting surfaces 37A of eachtwo of the first silicon members 34, 36, and 38. FIG. 7A illustrates theabutting surface 37A between the first silicon members 34 and 36, andFIG. 7B illustrates the abutting surface 37A between the second siliconmembers 48 and 52. A direction of an arrow in the figure indicates anoutside direction in a radial direction of the protective material ring46. Each of the joining parts 39 is provided at a center part except fora range of several mm from the outer edges of the abutting surfaces 37A,and is preferably provided at the center part except for a range of 1 mmor more from the outer edges of the abutting surfaces 37. Further, ajoining part 55 is also provided between the joining surface 54A of thefirst ring body 32 and the joining surface 54A of the second ring body47. Note that the joining part 39 may be provided between the abuttingsurfaces 37A of each two of the second silicon members 48, 50, and 52.

The silicon adhesion parts 40 are provided on the outer edges of theabutting surfaces 37A and on the outer edges of the joining surfaces 54Aof the first ring body 32 and the second ring body 47. When the siliconadhesion part 40 is applied to the protective ring 20, the siliconadhesion part 40 is preferably provided on parts that are not in contactwith the vacuum chamber 12, the upper-wall member 17, and the shieldingring 21 and are exposed inside the vacuum chamber 12, namely, on the topsurface side and the inner peripheral surface side of the protectivematerial ring 46. More specifically, the silicon adhesion parts 40 arepreferably provided on the top surface side and the inner peripheralsurface side of the protective material ring 46 out of the outer edgesof the abutting surfaces 37A of the first ring body 32, on the innerperipheral surface side of the protective material ring 46 out of theouter edges of the abutting surfaces 37A of the second ring body 47, andon inner peripheral surface side 57 of the protective material ring 46out of the outer edges of the joining surfaces 54A. The protective ring20 is mounted on the peripheral edge portion of the upper electrodeplate 14 so that the top surface at which the silicon adhesion parts 40are provided on the abutting surfaces 37A faces downward and the bottomsurface is in contact with the upper wall of the vacuum chamber 12.

As described above, each of the silicon adhesion parts 40 plugs the gapbetween the abutting surfaces 37A of each two of the first siliconmembers 34, 36, and 38 and the second silicon members 48, 50, and 52,and the gap between the joining surface 54A of the first ring body 32and the joining surface 54A of the second ring body 47.

Next, a method of manufacturing the protective material ring 46according to the present embodiment is described. Note that descriptionof steps similar to the steps according to the above-described firstembodiment is appropriately omitted. First, the three surface-treatedsecond silicon members 48, 50, and 52 are arranged in the ring shape.Next, an alloying metal foil is disposed on the top surfaces of thesecond silicon members 48, 50, and 52. Subsequently, the three firstsilicon members 34, 36, and 38 are placed on the alloying metal foil.The alloying metal foil is disposed between each two of the three firstsilicon members 34, 36, and 38. The first silicon members 34, 36, and 38are disposed so as to be out of position, by half of a length in alongitudinal direction, from the second silicon members 48, 50, and 52that have been already disposed. The first silicon members 34, 36, and38 are stacked on the second silicon members 48, 50, and 52 through thealloying metal foil in the above-described manner.

Next, heating is performed from the first silicon members 34, 36, and 38side, to generate a melt containing silicon and the alloying metalbetween the first ring body 32 and the second ring body 47 and betweenthe abutting surfaces 37A of each two of the first silicon members 34,36, and 38, thereby forming the joining parts 39 and 55. The heatingcondition and the cooling condition similar to the heating condition andthe cooling condition according to the above-described first embodimentare adoptable.

Next, the silicon between the abutting surfaces 37A of each of the firstring body 32 and the second ring body 47 and the silicon between thejoining surfaces 54A are heated and melted to form the silicon adhesionparts 40.

Since the protective material ring 46 according to the presentembodiment includes the silicon adhesion parts 40 between the abuttingsurfaces 37A and between the joining surfaces 54A, it is possible toachieve effects similar to the effects by the above-described firstembodiment.

The case where the silicon adhesion parts 40 are provided on the topsurface side and the inner peripheral surface side in the protectivematerial ring 46 out of the outer edges of the abutting surfaces 37A inthe first ring body 32, the inner peripheral surface side in theprotective material ring 46 out of the outer edges of the abuttingsurfaces 37A in the second ring body 47, and the inner peripheralsurface side 57 in the protective material ring 46 out of the outeredges of the joining surfaces 54A has been described in the presentembodiment; however, the present invention is not limited thereto. Thesilicon adhesion parts 40 may be provided on the top surface side andthe outer peripheral surface side out of the outer edges of the abuttingsurfaces 37A of the first ring body 32 or may be provided on the topsurface side, the inner peripheral surface side, and the outerperipheral surface side out of the outer edges of the abutting surfaces37A. The silicon adhesion parts 40 may be provided on the outerperipheral surface side in the protective material ring 46 out of theouter edges of the abutting surfaces 37A of the second ring body 47, theouter peripheral surface side in the protective material ring 46 out ofthe outer edges of the joining surfaces 54A, or the entirecircumferences of the outer edges of the joining surfaces 54A.

The case where the silicon adhesion parts 40 are provided between theabutting surfaces 37A and the joining surfaces 54A of the first ringbody 32 and the second ring body 47 has been described in the presentembodiment; however, the present invention is not limited thereto. Asillustrated in FIG. 8A and FIG. 8B, the silicon adhesion parts do notnecessarily need to be provided between the abutting surfaces 37B andthe joining surface 54B.

3. Third Embodiment

Next, a protective material ring according to a third embodiment isdescribed. A protective material ring 56 illustrated in FIGS. 9A and 9Bincludes a plurality of (three in this figure) first silicon members 58,60, and 62, and a plurality of (three) embedded silicon members 64A thatis each embedded at a position across each two of the first siliconmembers 58, 60, and 62. The embedded silicon members 64A are provided onside opposite to the side to be irradiated with plasma, of theprotective material ring 56. In this figure, the embedded siliconmembers 64A are provided on bottom surface side.

The embedded silicon members 64A are preferably made of the samematerial as the material of the silicon members. Four corners of each ofthe embedded silicon members 64A are preferably subjected to roundchamfering. The four corners of each of the embedded silicon members 64Aare subjected to the round chamfering, which makes it possible toprevent damage such as chipping. A radius of the round chamfering ispreferably 3 mm or more.

The embedded silicon members 64A are preferably formed such that bottomsurfaces thereof are substantially flush with the bottom surfaces of thesilicon members. A thickness of each of the embedded silicon members 64Ais preferably 20% to 80% of the thickness of the silicon members, and ismore preferably 40% to 60%.

Each of the embedded silicon members 64A is preferably formed of arectangular plate member, and preferably has a size not protruding fromthe protective material ring 56 in a planar view. A length in thelongitudinal direction of each of the embedded silicon members 64A ispreferably 2% to 10% of an outer peripheral length of the protectivematerial ring 56.

More specifically, the size of each of the silicon members can be set tothe size obtained by dividing a ring that has an inner peripheraldiameter of 330 mm, an outer peripheral diameter of 400 mm, and athickness of 10 mm, into three pieces. Each of the embedded siliconmembers 64A can be set to a length of 62 mm, a width of 25 mm, and athickness of 5 mm, and have the four corners subjected to the roundchamfering of 5 mm. Each of holes provided on the bottom surfaces of thesilicon members has a shape corresponding to a shape of each of theembedded silicon members and has a depth of 5 mm. In this case, thethickness of each of the embedded silicon members 64A is 50% of thethickness of each of the silicon members, and the length in thelongitudinal direction of each of the embedded silicon members 64A is 5%of the outer peripheral length of the protective material ring 56.

As illustrated in FIG. 10 , the holes each having a bottom surface areprovided at end parts in the longitudinal direction of each of thesilicon members, on the bottom surfaces of the silicon members. FIG. 10illustrates an abutting surface 63A between the first silicon members 58and 60. A direction of an arrow in the figure indicates an outsidedirection in a radial direction of the protective material ring 56. Theembedded silicon members 64A are embedded in the holes. A joining part68 is provided between a top surface of each of the embedded siliconmembers 64A and the corresponding first silicon members (bottom surfaceof hole). A silicon adhesion part 70 is preferably provided between theabutting surfaces 63A of each two of the first silicon members 58, 60,and 62. When the silicon adhesion parts 70 are applied to the protectivering 20, the silicon adhesion parts 70 are preferably provided on thetop surface side and the inner peripheral side of the protectivematerial ring 56 out of the outer edges of the abutting surfaces 63A.The protective ring 20 is mounted on the peripheral edge part of theupper electrode plate 14 so that the top surface on which the siliconadhesion part 70 is provided faces downward and the bottom surface is incontact with the upper wall of the vacuum chamber 12.

In the protective material ring 56 according to the present embodiment,heating is performed from the top surface side of the silicon members togenerate a melt containing silicon and the alloying metal, therebyforming the joining parts 68. Further, the silicon adhesion parts 70 atthe abutting surfaces 63A can be formed by a method similar to themethod according to the above-described first embodiment.

In the protective material ring 56 according to the present embodiment,the joining surface area between the silicon members can be increasedbecause the embedded silicon members 64A are provided. This makes itpossible to more increase mechanical strength. Further, the protectivematerial ring 56 can achieve effects similar to the effects according tothe above-described first embodiment because each gap between theabutting surfaces 63A is plugged with the silicon adhesion part 70.

Each of the embedded silicon members 64A is not necessarily formed inthe rectangular shape. Alternatively, for example, as illustrated inFIGS. 11A and 11B, an embedded silicon member 64B having a long-circleshape (FIG. 11A) or an embedded silicon member 64C having an arc shape(FIG. 11B) may be used. Further, each of end parts in the longitudinaldirection of each of the embedded silicon members 64B and 64C may be asemi-circular shape as illustrated in the same figure.

The case where each of the joining parts 68 is provided between each ofthe embedded silicon members 64A and the corresponding silicon members(bottom surface of hole) has been described in the present embodiment;however, the present invention is not limited thereto. As illustrated inFIG. 12A, a joining part 72 may be additionally provided between theabutting surfaces 63B of the silicon members.

The case where the silicon adhesion parts 70 are provided on the topsurface side and the inner peripheral surface side in the protectivematerial ring 56 out of the outer edges of the abutting surfaces 63A hasbeen described in the present embodiment; however, the present inventionis not limited thereto. The silicon adhesion part 70 may be provided onthe top surface side and the outer peripheral surface side out of theouter edges of the abutting surfaces 63A, or may be provided on theentire circumferences of the outer edges of the abutting surfaces 63A.

The case where the silicon adhesion parts 70 are provided between theabutting surfaces 63A of each two of the first silicon members 58, 60,and 62 has been described in the present embodiment; however, thepresent invention is not limited thereto. As illustrated in FIG. 12B, nosilicon adhesion part may be provided between the abutting surfaces 63C.

4. Modification

The present invention is not limited to the above-described embodiments,and can be appropriately modified within the scope of the presentinvention.

In the above-described embodiments, the case where the joining partcontains the alloying metal has been described; however, the presentinvention is not limited thereto, and the joining part may contain boronoxide. A method of manufacturing the protective material ring in thecase where the joining part contains boron oxide is described below withthe example of the joining surfaces.

First, three surface-treated silicon members are arranged in a ringshape in a manner similar to the above-described embodiments.Subsequently, the silicon members are heated to first temperature (180°C. to 280° C.), and a starting material made of particulate boric acid(B(OH)₃) is supplied to at least a part of the joining surfaces of thesilicon members. The silicon members can be heated by heating meansusing a common electric resistance heater. Since the temperature of thejoining surfaces is 180° C. to 280° C., dehydration reaction of boricacid occurs on the joining surfaces. Water is desorbed from boric acidin about 10 seconds to about 60 seconds, and metaboric acid (HBO₂) isaccordingly generated. Metaboric acid is dissolved into the desorbedwater to generate a liquid substance having excellent fluidity.

In a case where the temperature of the silicon members is excessivelylow, water cannot be desorbed from boric acid, and metaboric acid cannotbe obtained. In contrast, in a case where the temperature of the siliconmembers is excessively high, water is quickly desorbed from boric acid.As a result, boric acid supplied to the joining surfaces of the siliconmembers may be splattered or boric acid may be quickly solidified. Whenthe first temperature is 180° C. to 280° C., it is possible to moresurely obtain metaboric acid. The first temperature is preferably 200°C. to 240° C.

As the starting material made of particulate boric acid, granular boricacid having a diameter of 0.1 mm to 2 mm sold on the open market can beused as it is. When the starting material made of boric acid having adiameter of 0.1 mm to 2 mm is supplied to the top surfaces of thesilicon members heated to the first temperature, it is possible to forma layer containing metaboric acid described later. Boric acid ispreferably supplied little by little to a part of the top surfaces ofthe silicon members.

The liquid substance that has been generated through desorption of waterfrom boric acid is spread by a spatula to form the layer containingmetaboric acid. As described above, boric acid as the starting materialis supplied little by little to the joining surfaces of the siliconmembers, and the generated liquid substance is spread every time. As aresult, it is possible to form the uniform layer containing metaboricacid on the joining surfaces. A cut wafer is used as the spatula, whichmakes it possible to avoid mixture of impurity into the layer containingmetaboric acid.

A thickness of the layer containing metaboric acid is preferably 1 mm orless, and more preferably 0.1 mm to 0.5 mm. Generation of bubbles causedby dehydration reaction can be suppressed when heating is performed in asubsequent step as the thickness of the layer containing metaboric acidis smaller. The thickness of the layer containing metaboric acid can beadjusted by controlling an amount of boric acid to be supplied as thestarting material.

The silicon members that have been provided with the layer containingmetaboric acid on the joining surfaces are heated to increase itstemperature to second temperature (500° C. to 700° C.). As a result,water is further desorbed from metaboric acid, and a melt containingboron oxide (B₂O₃) is accordingly generated. In a case where the secondtemperature is excessively high, the silicon members may be cracked dueto difference of thermal expansion coefficients between boron oxide andsilicon when cooling is performed in a subsequent step. In the casewhere the second temperature is 500° C. to 700° C., it is possible tomore surely obtain the melt containing boron oxide. The secondtemperature is preferably 550° C. to 600° C.

The other surface-treated silicon members are bonded by pressing themelt containing boron oxide generated on a joining region of the siliconmembers in between. Pressure in press-bonding is not particularlylimited, and is appropriately settable. In a case where a width of eachof the silicon members is about 30 mm, the silicon members and the othersilicon members can be joined with a heat insulating material in betweenby pressing with hands.

When the melt of boron oxide is solidified, the silicon members and theother silicon members are joined to each other by the boron oxide layer.The melt is solidified, for example, when left at room temperature. Thejoining part is generated in the above-described manner to manufacturethe protective material ring.

The layer containing metaboric acid may be formed not over the entireregion of the joining surfaces of the silicon members but in a frameshape along an outer edge of the joining surfaces. The width of theframe-shaped layer containing metaboric acid can be 5 mm to 10 mm. Thealloying metal foil is disposed in a region inside the frame-shapedlayer containing metaboric acid. Before the alloying metal foil isdisposed in the inside region, the frame-shaped layer containingmetaboric acid may be cooled and the surface thereof may be polished toreduce the thickness. The frame-shaped layer containing metaboric acidis formed on the joining surfaces of the silicon members and thealloying metal foil is disposed.

Thereafter, the other silicon members are disposed, and the siliconmembers and the other silicon members are heated to eutectic temperatureor more and 700° C. or less. The alloying metal forms a eutectic withsilicon by the heating, which makes it possible to more firmly join thesilicon members to each other. The eutectic alloy formed at this time issurrounded by the frame-shaped boron oxide layer. Further providing thesilicon adhesion parts on the outer edges of the joining surfaces makesit possible to achieve effects similar to the effects by theabove-described first embodiment.

REFERENCE SIGNS LIST

-   10 Dry etching apparatus (substrate treatment apparatus)-   12 Vacuum chamber (treatment chamber)-   32, 46, 56 Protective material ring-   34, 36, 38, 58, 60, 62 First silicon member-   37A, 37B Abutting surface-   39, 55, 68, 72 Joining part-   40, 70 Silicon adhesion part-   48, 50, 52 Second silicon member-   54A, 54B Joining surface-   63A, 63B, 63C Abutting surface-   64A, 64B, 64C Embedded silicon member

The invention claimed is:
 1. A protective material ring comprising:three or more silicon members; and a joining part joining the siliconmembers, wherein the joining part consists of boron oxide: the siliconmembers comprise first and second silicon members abutting in onedirection and an embedded silicon member, wherein each of the first andsecond silicon members has an arc shape and has an upper surface and arear surface, and has a hole having a bottom surface at an end part in alongitudinal direction on the rear surface, the embedded silicon memberis embedded at a position across the first silicon member and the secondsilicon member abutting the first silicon member, wherein the embeddedsilicon member is a plate member, and is embedded in the hole of thefirst silicon member and the hole of the second silicon member; and thejoining part join the first silicon member, and the second siliconmember, and the embedded silicon member, wherein the joining part isprovided between the bottom surface of the hole of the first siliconmember and a top surface of the embedded silicon member and between thebottom surface of the hole of the second silicon member and the topsurface of the embedded silicon member.
 2. The protective material ringaccording to claim 1, further comprising a silicon adhesion partplugging a gap between the silicon members.
 3. The protective materialring according to claim 1, wherein the ring has an inner diameter of 320mm or more and an outer diameter of 800 mm or less.
 4. The protectivematerial ring according to claim 1, wherein the silicon members eachcontains monocrystalline silicon or polycrystalline silicon.
 5. Asubstrate treatment apparatus performing plasma treatment on asubstrate, the apparatus comprising: a treatment chamber; and theprotective material ring according to claim 1, wherein the protectivematerial ring is installed in the treatment chamber.
 6. A protectivematerial ring comprising: three or more silicon members; and a joiningpart joining the silicon members, wherein: the joining part contains anyone of Al, Ga, Ge, and Sn, and is a eutectic alloy with silicon; thesilicon members comprise first and second silicon members abutting inone direction and an embedded silicon member, wherein each of the firstand second silicon members has an arc shape and has an upper surface anda rear surface, and has a hole having a bottom surface at an end part ina longitudinal direction on the rear surface, the embedded siliconmember is embedded at a position across the first silicon member and thesecond silicon member abutting the first silicon member, wherein theembedded silicon member is a plate member, and is embedded in the holeof the first silicon member and the hole of the second silicon member;and the joining part join the first silicon member, and the secondsilicon member, and the embedded silicon member, wherein the joiningpart is provided between the bottom surface of the hole of the firstsilicon member and a top surface of the embedded silicon member andbetween the bottom surface of the hole of the second silicon member andthe top surface of the embedded silicon member.
 7. The protectivematerial ring according to claim 6, further comprising a siliconadhesion part plugging a gap between the silicon members.
 8. Theprotective material ring according to claim 6, wherein the ring has aninner diameter of 320 mm or more and an outer diameter of 800 mm orless.
 9. The protective material ring according to claim 6, wherein thesilicon members each contains monocrystalline silicon or polycrystallinesilicon.
 10. A substrate treatment apparatus performing plasma treatmenton a substrate, the apparatus comprising: a treatment chamber; and theprotective material ring according to claim 6, wherein the protectivematerial ring is installed in the treatment chamber.